Vision system for an autonomous vehicle

ABSTRACT

A system includes a vehicle management system, and at least a first, a second, and a third video camera in communication with the vehicle management system. The vehicle management system is configured to receive input from a combination of at least two cameras selected from among the first, second, and third video cameras based on an event associated with a vehicle to provide at least a first, a second, and a third visual depth of field.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application claims the benefit under 35 U.S.C. §119(e) ofU.S. Provisional Patent Application No. 60/805,197, entitled “VisionSystem for an Autonomous Vehicle,” filed on Jun. 19, 2006, which ishereby incorporated by reference herein in its entirety.

BACKGROUND

Autonomous and semi-autonomous vehicles have the potential to be used inan increasing number of applications. For example, the use of autonomousvehicles may be desirable in military or civilian applications thatwould otherwise expose human operators or passengers to dangerousenvironments. Such autonomous vehicles may include a control systemconfigured to receive information regarding, for example, thesurrounding terrain, upcoming obstacles, a particular path, etc., and toautomatically respond to this information in place of a human operatorby commanding a series of maneuvers so that the vehicle is able tonegotiate the terrain, avoid the obstacles, or track a particular pathwith little or no human intervention.

In certain applications, the autonomous vehicle may be required tooperate in a continuously changing environment. For example, theautonomous vehicle may be required to track a path over alternatestretches of flat, winding, or hilly terrain at varying speeds, andacross which many obstacles, such as other vehicles or various otherobjects, or even humans may appear at unexpected places or times.Without the presence of a human operator to assess the changingconditions, the autonomous vehicle may collide with an obstacle orotherwise attempt maneuvers beyond its reactive capabilities. In certainother applications, the autonomous vehicle may be required to operatewithout detection, such as in a military operation or even at night.Accordingly, it would be desirable to provide an improved autonomousvehicle that is configured to address these and other concerns.

SUMMARY

Autonomous and/or semi-autonomous vehicles are described herein. Thevehicles may be any suitable type or make of vehicle. The vehicle may bea military vehicle or a civilian vehicle. In either context, the vehiclemay be configured to transport large payloads over long distances and/oroff-road. The vehicle may include various subsystems such as a throttlesystem, transmission system, braking system, and/or steering system. Insome embodiments, the vehicle may include an all-wheel steering system,an independent suspension, and/or a compressed air system. Thecompressed air system may be used to operate the brakes and/or othervehicle subsystems.

The vehicle may include a vehicle control system that is used to operatethe vehicle autonomously. The vehicle control system may include avariety of sensors which gather information regarding the status of thevehicle, the environment around the vehicle (especially in front of thevehicle), the position of the vehicle, and so forth. A variety ofsystems may be used to provide information to the vehicle control systemto allow for autonomous operation of the vehicle. For example, suchsystems may include LIDAR systems (also referred to as LADAR systems ina military context), Radar systems, vision systems, GPS systems, and soforth.

The entire control system or various components thereof may be providedas part of a kit which is used to retrofit existing vehicles to makethem autonomous. This may be particularly desirable in situations wherethere are a fleet of vehicles (e.g., in a military or civilian context)that have similar configurations. For some vehicles that already includean electronic control system, the kit may simply include some sensorsand additional software (or hardware if needed). For those vehicles thatare largely controlled mechanically (mechanical steering, braking,throttle, etc.) the kit may include additional motors and/or other subcontrol systems for the vehicle.

The vehicle control system may include a vision system that is used todetect obstacles relative to the vehicle and/or identify a path for thevehicle to follow. The vision system may include a plurality of camerasthat are configured to receive input in the form of images of thesurrounding environment. The vision system may include a processor thatis configured to receive and process the images to extract usefulinformation about the surrounding environment. In a military context,one advantage of the vision system relative to other obstacle detectiontechniques such as LIDAR or radar is that the vision system does nottransmit electromagnetic radiation that can be detected and/or jammed bythe enemy.

In one embodiment, the vision system may include at least three cameras.The vision system may be configured to receive input from variouscombinations of the three cameras depending on the status of the vehicle(e.g., speed, steering angle, and so forth) or depending on thesurrounding environment (e.g., the rate that obstacles are detected, thesize of the obstacles, and so forth). For example, the three cameras maybe mounted on the vehicle so that the cameras are asymmetrically spacedapart from each other. Thus, the distance or baseline between eachcombination of two cameras is different. The vision system may beconfigured to use a combination of the cameras having a wide baseline inorder to detect obstacles that are relatively far away. The visionsystem may be configured to use a combination of cameras having ashorter baseline to detect obstacles that are closer to the cameras. Thereason for doing this is that objects that are far away from each othercan be identified and matched in images taken from cameras having a widebaseline. However, if the same objects are positioned much closer to thecameras, the wide baseline of the cameras results in the objects lookingvery different in the images. Thus, when the objects are nearby, camerashaving a shorter baseline may be used to make it easier to identify andmatch the object in the images taken from the cameras.

Other features and advantages of the subject matter described hereinwill become apparent from the following detailed description andaccompanying drawings. It should be understood, however, that thedetailed description and specific examples are given by way ofillustration and not limitation. Many modifications and changes withinthe scope of the present invention may be made without departing fromthe spirit thereof, and the invention includes all such modifications.

DRAWINGS

The exemplary embodiments will hereafter be described with reference tothe accompanying drawings, wherein like numerals depict like elements,and:

FIG. 1 is a perspective view of one embodiment of a vehicle that isautonomous and/or semi-autonomous.

FIG. 2 is a block diagram schematically illustrating a vehicle controlsystem according to an exemplary embodiment.

FIG. 3 is a front view of another embodiment of an autonomous and/orsemi-autonomous vehicle.

FIG. 4 is a front view of the vehicle in FIG. 3 which shows some of thesensors coupled to the roll cage and/or on or near the cab of thevehicle.

FIG. 5 is a front view of the vehicle in FIG. 3 which shows someadditional sensors positioned near the bumper of the vehicle.

FIG. 6 is a perspective view of another embodiment of an autonomousand/or semi-autonomous vehicle showing sensors positioned near the rollcage and the bumper.

FIG. 7 is a perspective view of the vehicle in FIG. 6 showing two LIDARsensors coupled to the bumper of the vehicle.

FIG. 8 is a perspective view of the vehicle in FIG. 6 showing a LIDARsensor and a camera coupled to the roll cage of the vehicle.

FIG. 9 is a perspective view of the interior of another embodiment of anautonomous and/or semi-autonomous vehicle showing at least a portion ofthe hardware for the vehicle control system positioned under thepassenger seat.

FIG. 10 is a perspective view of another embodiment of an autonomousand/or semi-autonomous vehicle.

FIG. 11 is a perspective view of the vehicle in FIG. 10 showing sensorspositioned near the lower front section of the vehicle.

FIG. 12 is a perspective view of the vehicle in FIG. 10 showing sensorscoupled to the cab of the vehicle.

FIGS. 13-15 are illustrations of the path planning, obstacle detection,and obstacle avoidance capabilities of another embodiment of anautonomous and/or semi-autonomous vehicle.

FIGS. 16-19 are pictures showing the obstacle detection capability ofthe vision system.

FIGS. 20A-20C are a series of pictures that show the path detectioncapability of the vision system.

FIGS. 21-23 are a series of pictures that show the ability of the visionsystem to detect obstacles in adverse lighting conditions.

DETAILED DESCRIPTION

Before turning to the FIGS. which illustrate the exemplary embodimentsin detail, it should be understood that the subject matter describedherein is not limited to the details or methodology set forth in thefollowing description or illustrated in the FIGS. The subject matterdescribed herein is capable of being provided in other embodiments orbeing practiced or carried out in various ways. It should also beunderstood that the phraseology and terminology employed herein is forthe purpose of description only and should not be regarded as limiting.Further, while the various exemplary embodiments are primarily describedin the context of autonomous vehicles, it should be understood thatother types of vehicles are contemplated as well, such assemi-autonomous vehicles and the like. The term “autonomous vehicle” asused herein generally refers to a vehicle configured for unmannedoperation, i.e., operation without a human pilot or co-pilot, with somelevel of autonomy built in, but which may or may not also carry one ormore human passengers. Semi-autonomous vehicles are those vehicles thatoperate to some degree in an autonomous fashion. For example, asemi-autonomous vehicle may be one which is capable of receiving remoteinstructions (e.g., via a wireless connection) from a person to operatethe vehicle in certain situations such as when the vehicle can no longeroperate autonomously for some reason.

It should be appreciated that the vehicles, control systems, features,advantages, and any other subject matter described in: (1) U.S. Pat. No.6,922,615, entitled “Turret Envelope Control System and Method for aFire Fighting Vehicle,” issued on Jul. 26, 2005, (2) U.S. Pat. No.6,885,920, entitled “Control System and Method for Electric Vehicle,”issued on Apr. 26, 2005, (3) U.S. Pat. No. 6,882,917, entitled “SteeringControl System and Method,” issued on Apr. 19, 2005, (4) U.S. Pat. No.6,421,593, entitled “Military Vehicle having Cooperative Control Networkwith Distributed I/O Interfacing,” issued on Jul. 16, 2002, and (5) U.S.Provisional Patent Application No. 60/723,363, entitled “Vehicle ControlSystem and Method,” filed on Oct. 4, 2005, may be used and/orincorporated with the subject matter described herein. All possibleconfigurations of the subject matter described in these documents andthe subject matter described herein is contemplated and hereby expresslydisclosed. For example, any of the vehicles or any portion of any of thevehicles (e.g., vehicle control systems, components for vehicle controlsystems, etc.) in these documents with their various configurations,control systems, features, and components may be combined with all orany part of the subject matter described herein. The documents (1)-(5)listed in this paragraph are hereby incorporated by reference herein intheir entireties as if the entire contents of these documents werereproduced herein.

Referring to FIG. 1, one embodiment of an autonomous vehicle 102 isshown. The vehicle 102 is a tactical wheeled vehicle that may be used ina military context to transport troops, supplies, or any other goods.The vehicle 102 has eighteen inches of ground clearance and is capableof traversing rugged terrain. The vehicle 102 may have features such asall-wheel drive, all-wheel steering, independent suspension (all or someof the wheels), and a central tire inflation system. Many of thesefeatures make it easier for the vehicle 102 to operate autonomously. Forexample, since the vehicle 102 is relatively large, the addition ofall-wheel steering allows the vehicle 102 to maneuver quickly and withmore agility to avoid obstacles, pass through tunnels, etc. Also, thecentral tire inflation system may be used to help the vehicle 102 getunstuck by reducing the air pressure in the tires and thereby increasingthe traction of the vehicle 102.

The vehicle 102 may also be configured to handle about 60% grades andabout 30% side slopes while the vehicle 102 is fully loaded. The vehicle102 may be capable of carrying about a seven ton payload off-road andabout a fifteen ton payload on-road. The vehicle 102 may also be capableof fording five feet of water, traveling up to and above about 65 milesper hour, and cruising for a range of about 300 miles or more.

The vehicle 102 may be provided in a dump truck configuration where thebed pivots upward to unload material in the bed of the truck. Thevehicle 102 may also be configured as a wrecker vehicle that is capableof towing disabled vehicles such as tanks or other trucks to berepaired. The vehicle 102 may also include a flat bed and an articulatedlifting system. The lifting system may be configured to move supplies orother goods onto the flat bed. The lifting system folds up near the endof the bed in a stowed position while the vehicle 102 is traveling. Thevehicle 102 may include a load handling system that is capable ofreceiving and securely transporting standard or custom sized shippingcontainers. In one embodiment, the vehicle 102 may be the mediumtactical vehicle replacement (MTVR) manufactured by Oshkosh TruckCorporation, Oshkosh, Wis. The vehicle 102 may include any of thevarious commercial embodiments of the MTVR such as the cargo truckembodiment (regular and extended), dump truck embodiment, wreckerembodiment, HIMARS resupply vehicle embodiment, tractor embodiment,and/or load handling system embodiment.

In a military context there are some challenges to and advantageous ofusing an autonomous vehicle. For example, one of the challenges is thatmany of the technologies used to sense the terrain around the vehiclerely on the transmission of electromagnetic radiation (e.g., LIDAR,radar). The radiation can be detected by the enemy and used as a signalto guide bombs or other munitions to the autonomous vehicle. Also, theenemy may be able to jam the signals and cause the vehicle to crash orotherwise be disabled. The principle advantage of an autonomous vehiclein a military context is that fewer people need to be put in danger inorder to transport supplies and goods.

Although the vehicle 102 is described in the context of a militaryvehicle, it should be appreciated that the subject matter describedherein may be used with any of a number of suitable vehicles regardlessof whether they are civilian or military vehicles, heavy duty or lightduty vehicles, or large or small vehicles. For example, the subjectmatter described herein may be used with the firefighting vehiclesdescribed in some of the documents that are incorporated by referenceabove.

The vehicle 102 may be configured to be easily switched from manualoperation to autonomous operation. The switchover may be as simple aspressing a button or may involve some amount of mechanical or electricalreconfiguration. Allowing the vehicle 102 to be used in both manual andautonomous mode increases the usability of the vehicle 102. For example,in a military context, if the vehicle 102 is inoperable in autonomousmode due to enemy fire, the vehicle 102 may still be capable of beingoperated manually. Also, the vehicle 102 may be capable of beingoperated by an operator until the vehicle 102 enters a dangerous area(e.g., vehicle approaches the enemy, vehicle enters a hazardous wastearea) at which point the vehicle may be operated autonomously.

FIG. 2 is a block diagram schematically illustrating a vehicle controlsystem 100 for use with the vehicle 102 according to an exemplaryembodiment. The vehicle control system 100 may include a terraindetection system 104, a vehicle management system 106, and a systemmanager 108. The vehicle control system 100 also includes a plurality ofvehicle subsystems 110, position sensors 150, and terrain sensors 160.The vehicle control system 100 is generally configured to acquire andprocess vehicle position information and terrain information from theposition sensors 150 and the terrain sensors 160 to control the vehicle102 autonomously.

Referring to FIG. 9, certain hardware components of the vehicle controlsystem 100 may be positioned under the passenger seat 101 of the vehicle102. The hardware components may be packaged in a shock absorbing rackthat fits inside the passenger seat 101. In one embodiment, the vehicle102 may include a temperature control system that is configured to heatand/or cool the hardware components. For example, the vehicle 102 may beconfigured to air condition the space under the passenger seat 101 toprevent the microprocessors from overheating. The vehicle 102 may beconfigured to heat and/or cool the space that contains the hardwarecomponents using the heating and cooling systems used to control theclimate in the cab of the vehicle 102.

The terrain detection system 104 is used to detect obstacles around thevehicle 102 (e.g., rocks, sudden drop-offs, trees, and so forth) and/ordetect a path for the vehicle 102 to travel (e.g., detect a road). Theterrain detection system 104 receives and analyzes input from theterrain sensors 160 to identify obstacles and a path for the vehicle 102to follow. Terrain data from the various terrain sensors 160 is mergedinto a single database that is used to plan the path of the vehicle 102.

The terrain detection system 104 includes a first LIDAR system 103, asecond LIDAR system 105, and a vision system 107. The first LIDAR system103 receives input from two single-plane LIDAR sensors 162, 164 coupledto the vehicle 102. The second LIDAR system 105 receives input from twomulti-plane LIDAR sensors 166 coupled to the vehicle 102. The visionsystem 107 receives input from three cameras 168, 170, 172 coupled tothe front of the vehicle 102. It should be appreciated that the number,configuration, and types of terrain sensors used to provide input to theterrain detection system 104 may be varied widely. For example, theterrain detection system may include a radar system, or may includeadditional LIDAR systems, or may include a rotating array of LIDARsensors to provide a 360° view of the surrounding terrain. Likewise, theterrain sensors 160 may include a radar antenna, various cameras (stilland/or video cameras), and multiple LIDAR sensors (e.g., single plane ormulti-plane LIDAR systems). Also, the vehicle 102 may include any ofthese sensors in any configuration coupled to the rear of the vehicle102 to facilitate operation of the vehicle 102 in reverse.

The terrain sensors 160 may be mounted to the vehicle 102 using anysuitable mounting structure. For example, as shown in FIG. 12, theterrain sensors 160 may be mounted to the vehicle using telescopicallyadjustable mounts 157 that move in and out via a threaded engagementsystem. The adjustable mounts 157 allow for precise adjustment of theterrain sensors 160 but also keep the terrain sensors 160 in a fixedposition after the adjustment has been performed. The adjustable mounts157 may be used to hold any of the terrain sensors 160 and/or positionsensors 150 in place. The terrain sensors 160 and/or position sensors150 may be coupled to a roll bar or roll cage 180 of the vehicle. Theroll bar may also serve as a protective conduit for the sensorcommunication wires and power wires to travel.

As shown in FIGS. 3-4, the LIDAR sensors 162, 164 are coupled to theoutside edges of the roll bar 180 at the front of the vehicle 102. TheLIDAR sensors 162, 164 are positioned so that they point about 10degrees down and about 25 degrees outward to the side of the vehicle102. Positioning the LIDAR sensors 162, 164 in this fashion providesgood coverage of the terrain to the front and the side of the vehicle102. This allows the vehicle 102 to make tight turns while still havingsome information regarding the terrain in the direction that the vehicle102 is turning. It should be appreciated that the LIDAR sensors 162, 164may be positioned at any suitable position to provide the most usefulinformation to the vehicle control system 100. To some extent, theorientation of the LIDAR sensors 162, 164 depends on the type of vehiclebeing used (e.g., taller vehicles may require the LIDAR sensors to bepointed down more). The LIDAR sensors 162, 164 may be configured to bepositioned about 0 to 20 degrees down and about 0 to 90 degrees outwardto the side of the vehicle 102. Also, the LIDAR sensors 162, 164 may beconfigured to scan a 100 degree scan area with a 1 degree resolution.Suitable LIDAR sensors may be obtained from SICK, having an office inMinneapolis, Minn., as model number SICK LMS-291.

The first LIDAR system 103 may be configured to detect positiveobstacles (e.g., obstacles that protrude upward) and negative obstacles(e.g., road edges, cliffs, etc.). The positioning of the LIDAR sensors162, 164 should allow for detection of both positive and negativeobstacles. The first LIDAR system 103 processes the scan data from theLIDAR sensors 162, 164 to identify positive and negative obstacles.Positive obstacles may be detected by translating the raw scan data froma sensor level coordinate framework to a local level coordinateframework and comparing the relative heights of neighboring scan points.A history of scan data can be used to effectively map the surface infront of the vehicle 102. An obstacle is identified if the surface asdetected by the LIDAR sensors 162, 164 protrudes upward above athreshold amount. The detection threshold may be set at a minimumobstacle height based on the capabilities of the vehicle 102. Forexample, the vehicle 102 as shown in FIG. 1 may be configured to have adetection threshold of about eighteen inches since the vehicle 102 candrive over any obstacle that is under eighteen inches. A convex hullalgorithm may be used to define the outermost edge of the obstacle. Oncethe obstacle and its outermost edges have been identified, the vehiclecontrol system 100 can store the obstacle in the database.

The first LIDAR system 103 may detect negative obstacles in a mannerthat is similar to detecting positive obstacles. The data map of thesurface in front of the vehicle 102 may be searched using an algorithmthat identifies any negative height discontinuities. Any identifiednegative height discontinuities are evaluated further to determine ifthe edge of the discontinuity is a continuation of a previously detectededge.

It should be appreciated that many aspects related to the first LIDARsystem 103 and the single-plane LIDAR sensors 162, 164 may be modifiedin a variety of ways. For example, instead of using single-plane LIDARsensors, multi-plane LIDAR sensors may be used. Also, more or less thantwo LIDAR sensors 162, 164 may be used (e.g., one or more additionalLIDAR sensors may be coupled to the rear of the vehicle 102 to assistwith backing the vehicle 102). The LIDAR sensors 162, 164 may be coupledto the vehicle at any suitable location such as the cab, fender, and soforth.

Referring to FIGS. 3, 5, and 7, the multi-plane LIDAR sensors 166 usedwith the second LIDAR system 105 are coupled to the vehicle 102 near thebumper 182. Each of the LIDAR sensors 166 are four plane scanner devicesthat are used primarily for positive obstacle detection at long andclose range. Each LIDAR sensor 166 is positioned horizontally so thattwo planes scan toward the ground and two planes scan toward the sky.Desirably, the LIDAR sensors 166 each have a range of about 80 meters, aresolution of about 0.25 degrees, and a 170 degree scan area. The largescan area allows the LIDAR sensors 166 to be used to identify obstaclesaround upcoming turns.

As shown in FIG. 1, the vehicle 102 may be configured to include only asingle LIDAR sensor 166. However, it may be desirable to include atleast two LIDAR sensors 166 so that in case one of the LIDAR sensors 166is damaged or otherwise unable to be used, the remaining LIDAR sensor166 can still provide information to the vehicle control system 100.

The second LIDAR system 105 is configured to receive scan data from theLIDAR sensors 166 and identify obstacles by searching for large positiveslopes in the scan data. The obstacle detection algorithm used toprocess the scan data in the first LIDAR system 103 is similar to theobstacle detection algorithm used to process the scan data in the secondLIDAR system 105. In one embodiment, the same algorithm may be used toprocess scan data from both sources. The second LIDAR system 105 may beconfigured to translate the scan data from the coordinate frame of theparticular LIDAR sensor 166 to a local level coordinate frame and storedin the database. Since the LIDAR sensors 166 are multi-plane devices,the scan data from each plane may be compared to each other to aid indetecting obstacles and false positives. Since the scan data has beentranslated into a local level coordinate frame, the position ofobstacles identified in the scan data from the LIDAR sensors 166 can becompared to the position of obstacles identified using the other terrainsensors 160 and to the position of the vehicle 102.

The LIDAR sensors 162, 164 and the LIDAR sensors 166 may be configuredto scan the same area or different areas in front of the vehicle 102. Inone embodiment, the LIDAR sensors 162, 164, 166 are used to scanoverlapping areas in front of and to the side of the vehicle 102. Inanother embodiment, the LIDAR sensors 162, 164 may be configured to scanfor obstacles that are 0 to 20 meters in front of the vehicle 102 andthe LIDAR sensors 166 may be configured to scan for obstacles that are20 to 60 meters in front of the vehicle 102. Obstacles detected by theLIDAR sensors 162, 164, 166 may be put into an obstacle database thatthe vehicle control system 100 uses to plan the path of the vehicle 102.

The vision system 107 may be based on a multi stereoscopic visionsystem. The vision system 107 receives input from the cameras 168, 170,172, which are coupled to a horizontal portion of the roll bar 180. Thecameras 168, 170, 172 are coupled to the vehicle 102 in a secure mannerto prevent the cameras from becoming dislodged during operation of thevehicle 102. This may especially be a problem when the vehicle 102operates in an off-road environment.

The cameras 168, 170, 172 are coupled to the vehicle 100 so that theyare asymmetrically spaced apart from each other. As shown in FIG. 4, thecameras 168, 172 are positioned about 1.5 meters apart from each otherwhile the camera 170 is positioned about 0.5 meters from the camera 168.In one embodiment, the cameras 168, 170, 172 may be video cameras thattransmit images using ordinary light to the vision system 107. Inanother embodiment, the cameras 168, 170, 172 may be still cameras thatperiodically take pictures at the same time. The pictures may betransmitted to the vehicle control system 100 where the pictures areprocessed to identify obstacles and/or find a path for the vehicle 102.In yet another embodiment, the cameras 168, 170, 172 may be infraredcameras (either video or still). In yet another embodiment, the cameras168, 170, 172 may be video cameras capable of providing video streams at10 Hz (640×480, color with Bayer pattern).

The orientation of the cameras 168, 170, 172 may be calibrated using agraduated grid. This may be done to fix the three degrees of freedomspecifying the cameras orientation to known values. In one embodiment,the yaw and roll angles of the cameras 168, 170, 172 are fixed at zero.This may help to reduce the processing requirements of the images takenby the cameras 168, 170, 172. The pitch angle of the cameras 168, 170,172 may be chosen so that the cameras 168, 170, 172 frame a smallportion over the horizon (to limit direct sunlight) and frame theterrain at about four meters from the vehicle 102. FIGS. 18-23 showimages taken with the pitch of the cameras 168, 170, 172 being adjustedin this manner.

It should be appreciated that the cameras 168, 170, 172 may be coupledto the vehicle 102 in any suitable fashion and location. For example,additional cameras may be coupled to the rear and side of the vehicle102 to facilitate backing and turning of the vehicle 102. Also, thepitch, yaw, and roll of the cameras 168, 170, 172 may be adjusted in anysuitable fashion.

As shown in FIG. 2, the cameras 168, 170, 172 send three video streamsto the vision system 107 via fire wire connections. The vision system107 selects which stereo pair of video streams to use depending on thespeed of the vehicle 102. By selecting different pairs of cameras, thevision system 107 can obtain images from stereo pairs of cameras havingdifferent baselines (i.e., the distance between the cameras). It isdesirable to have the ability to vary the baseline because when thebaseline is wider, the vision system 107 is able to more accuratelydetermine the distance to an object, but as the baseline increases, itmakes it more difficult to stereo match objects (especially closeobjects) in the images because the objects are viewed at very differentangles. Therefore, the vision system 107 is configured to receive thevideo streams from cameras 168, 172 when the vehicle 102 is traveling athigh speeds so that the vision system 107 can accurately identify andmeasure the distance of obstacles that are a long distance away. Whenthe vehicle 102 is traveling at medium speeds and obstacles are notapproaching as quickly, the vision system 107 is configured to receivethe video streams from cameras 170, 172. Likewise, when the vehicle 102is traveling at slow speeds, the vision system 107 is configured toreceive the video streams from cameras 168, 170 in that order. Thisconfiguration allows the vision system 107 to obtain images from camerashaving a wide baseline when the vehicle 102 is moving at high speeds,obtain images from cameras having a medium baseline when the vehicle 102is moving at medium speeds, and obtain images from cameras having ashort baseline when the vehicle 102 is moving at slow speeds.

The use of at least three cameras 168, 170, 172 fixed in positionprovides a mechanically robust system that is capable of providingimages from different combinations of the cameras 168, 170, 172. Inother embodiments, the vision system 107 may be configured to receiveinput from two cameras where at least one of the cameras rotates andtilts as the speed of the vehicle 102 changes instead of using the threecamera configuration. The moving cameras provide more accurate distanceestimation and better object matching versus a two camera configurationwhere the cameras do not move. However, the configurations that use atleast three fixed cameras are preferred since they allow the visionsystem 107 to receive different combinations of video streams fromcameras having different baselines and they do not rely on movement ofthe cameras—an area that is more prone to failure and/or that mayintroduce variations in the video streams.

It should be appreciated that the vehicle control system 100 may includeadditional LIDAR systems or may combine the first LIDAR system 103 andthe second LIDAR system 105 into a single LIDAR system. It should alsobe appreciated that the data from the LIDAR and vision systems may beprocessed by a single processor and/or single software program. Itshould also be appreciated that in other embodiments the data from eachLIDAR system and vision system may be initially processed using aseparate system. The output from each system may then be compared tocreate a database of obstacles. It should also be appreciated that eachof these systems may be provided as a separate module that mayoptionally be included with the vehicle control system 100. Providingeach system as a separate module may allow for greater flexibility inselecting the components of the vehicle control system 100 to use with aparticular type of vehicle.

The vision system 107 may be used to detect obstacles and detect a pathof travel for the vehicle 102. The images provided by the video streamsare subjected to V-disparity image analysis to determine the averageterrain slope in front of the vehicle 102. Slope information is thenused for both obstacle detection and path detection. Any significantdeviation from the average smooth slope detected previously isidentified as an obstacle. The exact location of the obstacles is thenobtained via stereo triangulation between the two views of the obstacle.This method provides a fairly precise position of the obstacle. However,the vehicle control system 100 may also compare the position of theobstacle as determined by the vision system 107 with the position of theobstacle as determined by the first LIDAR system 103 and/or the secondLIDAR system 105 to provide an even more accurate position of theobstacle.

This method allows the vision system 107 to detect thin vertical postssuch as fence posts. Although the vision system 107 may be capable ofdetecting small obstacles, the vision system 107 may be tuned with highthresholds to reduce the number of false positives. In other words, thecapability of detecting small obstacles may be traded for a higherrobustness of detection.

FIGS. 16-19 show pictures highlighting obstacles detected by the visionsystem 107. Each of FIGS. 16-19 includes two pictures—the one on theleft is the image before the obstacles are detected and the one on theright is the same image with the obstacles highlighted. The differentcolors of the obstacles represent the distance to the obstacle from thevehicle 102 (orange are the closest, red the next closest, and purpleare the farthest). As shown in FIGS. 16-19, posts and thin poles aredetected by the vision system 107.

The vision system 107 also uses image disparity analysis as the initialstep in detecting a path for the vehicle 102 to travel. Image disparityanalysis is used to compute the area in front of the vehicle 102 whichfeatures a smooth slope, which is known as the free-space. Free space isobtained using standard image warping to localize deviations from asmooth road surface. FIGS. 20A-20C show the left image, the warped rightimage, and the matching cluster representing free space.

The vision system 107 combines the free space with other features of theimages such as similarity in texture, similarity in color, similarity inshape to construct a representation of a path to follow. The pathdetection algorithm of the vision system 107 is also configured toindicate whether the path is straight so that the vehicle 102 mayincrease speed. When a curved path is present, the vehicle 102 isconfigured to slow down.

The cameras 168, 170, 172 may be configured to compensate for differentlights levels using automatic gain control, which allows the cameras168, 170, 172 to sense the environment including direct sunlight intothe cameras 168, 170, 172. FIGS. 21-23 show examples of images capturedwith and without gain control. FIGS. 22-23 show the result of obstacledetection by the vision system 107 in bad light conditions. As shown inFIGS. 22-23, obstacles may still be detected up until they enter theoversaturated area. The cameras 168, 170, 172 may also be provided withsun shades 186 which reduce the amount of direct sunlight that hits thecameras 168, 170, 172 to avoid oversaturation and reflections due todirty glass. The vehicle 102 may also include shields or reflectors 188that reflect sunlight away from the area of the cameras 168, 170, 172and the LIDAR sensors 162, 164 to prevent these devices from becomingtoo hot. In one embodiment, the shield 188 is a reflective diamondplating material (e.g., aluminum or steel). Additional shields 189 maybe provided in the vicinity of the LIDAR sensors 166.

The vehicle 102 may include a cleaning system that is configured toclean the lenses on the cameras 168, 170, 172 and/or the lenses of theLIDAR sensors 162, 164, 166. The cleaning system may include one or morenozzles that are aimed at the lenses. The nozzles may be configured todispense any suitable gas or liquid onto the lens to clean it. In oneembodiment, the cleaning system may be configured to include an airknife that directs high velocity bursts of air onto the lenses to removeany dust or other debris. The use of air may be desirable since liquidsmay attract dust and dirt and/or leave spots on the lenses. In anotherembodiment, the cleaning system may be configured to direct water oranother liquid (e.g., windshield washer fluid, and so forth) towards thelens. The cleaning system may then direct air over the lens to quicklydry the lens and remove the water. The air may be supplied by acompressed air system that is included as part of the vehicle 102. Inanother embodiment, the cleaning system may comprise a cleaningcontroller, one or more valves (e.g., an array of valves), and a washertank. The cleaning controller may be configured to electronicallycontrol the valves to direct liquid and/or air through the nozzles andonto the lenses.

The vehicle management system 106 includes a path planning module 200, avehicle control module 202, a navigation module 204, and an informationdatabase 206. The vehicle management system 106 is configured to receiveinput from the terrain detection system 104 and control the vehicle 102to reach a desired location. The vehicle management system 106 may alsoinclude a modeling and simulation system that is used to determine thecapabilities of the vehicle 102 under different circumstances. Themodeling and simulation system may be similar to that described in U.S.Provisional Patent Application No. 60/723,363, entitled “Vehicle ControlSystem and Method,” filed on Oct. 4, 2005, which is hereby incorporatedherein by reference in its entirety.

The navigation module 204 may be configured to compute the presentposition of the vehicle 102 and perform dead reckoning navigation. Deadreckoning navigation may be needed when the vehicle 102 is unable toreceive GPS signals (e.g., when the vehicle 102 is in a tunnel, etc.).The navigation module 204 may also include navigation relatedinformation such as maps (e.g., road maps, topographical maps, and thelike), aerial photographs, a list of GPS waypoints, and the like. Thisinformation may be utilized by the navigation module 204 to drive thevehicle 102 to its destination. In one embodiment, each mission may beplanned out by setting a plurality of GPS waypoints and a preferred pathof travel that the vehicle 102 should take until it reaches its finaldestination. The GPS waypoints and preferred path may be loaded into thenavigation module 204 prior to the vehicle 102 embarking on the mission.During the mission, the vehicle control system 100 is configured todrive the vehicle to successive waypoints while trying to stay on thepreferred path as much as possible while still avoiding any obstaclesthat may present themselves.

The navigation module 204 receives input from the position sensors 150.In the embodiment shown in FIG. 2, the position sensors 150 include dualGPS/inertial measurement units (IMU) 152 and a differential GPS unit154. The GPS/IMU units 152 may include a six-axis inertial measurementsystem which includes three angular rate sensors (gyros) and threeaccelerometers. The three accelerometers are all mounted at 90 degreesto each other, and the three angular rate sensors are mounted at thesame angles as their respective accelerometers. Together they give full3D motion measurement of the vehicle 102. The GPS/IMU units 152 are alsocapable of receiving GPS signals directly from GPS satellites anddifferential GPS information from the differential GPS unit 154. Theinformation provided to the navigation module 204 is used to chart thecourse of the vehicle 102 at a high level. The vehicle 102 attempts tofollow the course as much as possible while avoiding obstacles andattempting to stay on a road or other path.

Input from the inertial measurement system may be used by the vehiclecontrol system 100 to perform dead reckoning navigation. The inertialposition information provided to the vehicle control system 100 may besupplemented with other data such as wheel speed and time traveled(e.g., to determine distance traveled during dead reckoning navigation),wheel speed and steering angle (e.g., to determine direction the vehicle102 is going during dead reckoning navigation), or any other informationthat may be useful to determine the position of the vehicle 102. Also,the inertial position information may be used to measure the pitch androll of the vehicle 102. In one embodiment, the vehicle control system100 may be configured to perform dead reckoning navigation using sensedwheel speed and wheel angle for those situations where the GPS and IMUunits are not operational. The GPS/IMU units 152 may be positioned onthe approximate centerline of the vehicle 102 (e.g., in the floor of thecab). In one embodiment, the GPS/IMU units 152 may be obtained fromOxford Technical Solutions, Ltd., having an office in Dearborn, Mich.,as part number OXTS RT3100.

In the embodiment shown in FIG. 2, the vehicle 102 includes two GPS/IMUunits 152. Two of the units 152 may be provided so that the positioninformation (both GPS and inertial) received from each unit can beaveraged to provide a more accurate and robust calculation of theposition of the vehicle 102. Also, if one of the GPS/IMU units 152fails, the remaining GPS/IMU unit 152 could still be used to provideposition information to the vehicle control system 100. The vehiclecontrol system 100 may be able to determine that one of the GPS/IMUunits 152 has failed when, for example, the unit 152 stops providinginput or the input is so different from the position informationprovided by the other position sensors 150 and terrain sensors 160 thatthe input can no longer be trusted. If the vehicle control system 100determines that one of the GPS/IMU units 152 has failed, the vehiclecontrol system 100 uses the remaining GPS/IMU unit 152.

The differential GPS unit 154 is configured to receive differentialcorrections and send them to the GPS/IMU units 152. The differential GPSunit 154 may be configured to receive Beacon, SBS/WAAS, and/or Omnistarcorrections, as well as any other suitable corrections. It should beappreciated that the combination of GPS units may be varied widely. Forexample, the GPS/IMU units 152 may be capable of receiving thedifferential corrections directly without using a separate receiver.Likewise, the GPS/IMU units 152 may be split into two units so that theGPS unit is separate from the IMU unit.

The vehicle control module 202 is configured to interface with thevehicle subsystems 110 to allow the vehicle components to be controlledby the vehicle management system 106. As shown in FIG. 2, the vehiclesubsystems 110 may include a steering system 112, a braking system 116,a throttle system 120, and a transmission system 124.

The steering system 112 may include a servo drive 113 and acorresponding servomotor 114 that is in communication with the servodrive 113. The servo drive 113 may be configured to receive and processposition commands from the vehicle control system 100 and providecorresponding outputs (e.g., an analog voltage or current) to theservomotor 114. In response, the servomotor 114 may drive one or moreassociated wheels of the vehicle 102 to a desired steering angle. Thesteering system 112 may also include one or more wheel angle sensorsthat are used to determine the steering angle of a wheel of the vehicle102 and provide feedback to the vehicle control system 100 as to thecurrent steering angle of the wheel. In another embodiment, theservomotor 114 may include an integrated high-resolution encoder that isused to control the steering angle of the vehicle 102. It should also beappreciated that the encoder may be coupled to the steering system 112at any location that is capable of providing a reliable and accuratemeasurement of the steering angle of the wheels (e.g., steering column,etc.).

In one embodiment, the servomotor 114 is coupled directly to thesteering gearbox of the vehicle 102. The steering gearbox may beconfigured to have dual inputs so that the servomotor 114 and the handwheel can both be connected to the steering gear. This allows steeringcontrol of the vehicle to be switched between manual mode (operated by adriver) and autonomous mode without disassembling the steering system.

The steering system 112 may also be an all-wheel steering system, or inthe case of 6×6 wheeled vehicles, 8×8 wheeled vehicles and so on, thesteering system 112 may be configured to steer one, two, three, four, ormore sets of wheels. The steering system 112 may be configured similarlyto any of the steering systems described in U.S. Pat. No. 6,882,917(incorporated by reference herein previously).

The braking system 116 may include, for example, an anti-lock brakesystem including an anti-lock brake control system and anti-lock brakescoupled to one or more wheels of the vehicle 102. The braking system 116may be configured to receive braking commands, such as a “brake ON”command, from the vehicle control system 100. In response, the brakingsystem 116 may apply braking pressure to one or more wheels of thevehicle 102 to, for example, reduce the speed of the vehicle 102 orbring the vehicle 102 to a stop. According to an exemplary embodiment,braking pressure for the braking system 116 may be provided by acompressed-air system. The compressed-air system may include, forexample, an air compressor coupled to the power train of the vehicle 102(such as via gears, v-belt, etc. to convey rotational mechanical energyto the air compressor to be converted to air pressure), and one or moreair pressure tanks for storing compressed air from the air compressor.

It should be noted that for purposes of this disclosure, the term“coupled” means the joining of two members directly or indirectly to oneanother. Such joining may be stationary in nature or movable in nature.Such joining may be achieved with the two members or the two members andany additional intermediate members being integrally formed as a singleunitary body with one another or with the two members or the two membersand any additional intermediate member being attached to one another.Such joining may be permanent in nature or alternatively may beremovable or releasable in nature.

As shown in FIG. 2, the vehicle control system 100 may be configured tocommunicate with the braking system 116 via Ethernet to a proportionalvoltage to pressure valve. The braking system 116 may be configured toapply the service brakes in an amount that is proportional to thedeviation between the actual speed of the vehicle 102 and the desiredspeed of the vehicle 102. It should be appreciated, however, thatnumerous other configurations may also be used to control the brakingsystem 1 16. For example, the vehicle control system 100 may beconfigured to control the braking system 116 using more mechanicalcomponents such as a hydraulic actuator that operates the brakes throughthe system.

The braking system 116 may also include an engine brake. The brakingsystem 116 in combination with the throttle system 120 may be used tocontrol the speed of the vehicle 102. Typically, the speed of thevehicle 102 is controlled solely using the throttle. However, theservice brakes and the engine brake may be used to control the speed ofthe vehicle 102 on steep grades and/or to manage the speed that thevehicle 102 decelerates.

The throttle system 120 may include an engine control module and athrottle actuator. The engine control module may be configured toreceive and process throttle commands from the vehicle control system100 and provide corresponding outputs (e.g., an analog voltage orcurrent) to the throttle actuator. In response, the throttle actuatormay adjust the rotational speed of an engine coupled to the drive trainof the vehicle 102 to achieve a desired speed of the vehicle 102. Theengine control module may be configured to determine the speed of thevehicle 102 (e.g., using a tachometer feedback signal) and providefeedback to the vehicle control system 100 as to the current speed ofthe vehicle 102. In other embodiments, the speed of the vehicle 102 maybe determined using feedback from the transmission system 124 or bymeasuring the rotation of a drive shaft, or some other component of thepower train of the vehicle 102. In one embodiment, the vehicle controlsystem 100 and/or the engine control module may use a pulse widthmodulated (PWM) signal to provide very precise control of the throttle.

The throttle system 120 may be configured to so that reset conditions tothe throttle position are provided for transmission up shift and downshift and to activate the engine brake. Since the engine brakes aretypically activated when the when the engine is idling, throttleposition overrides are used whenever the engine brakes are active.Throttle position faders are used to reactivate the throttle positioncontrol when the engine brake is disabled.

The transmission system 124 may include the engine control module and atransmission mechanically coupled to the engine of the vehicle 102. Incombination, the transmission system 124 and the engine of the vehicle102 form the power train of the vehicle 102. The engine control modulemay be configured to receive and process gear change commands from thevehicle control system 100 and provide corresponding outputs (e.g., ananalog voltage or current) to the transmission system 124. In response,the transmission may change gears to achieve a desired rotational speedof the power train of the vehicle 102. In another embodiment, thetransmission system 124 may include a transmission control module thatis separate from the engine control module. The transmission controlmodule may be in communication with the engine control module so thatinformation required for shifting gears and so forth can be communicatedbetween the transmission control module and the engine control module.

As shown in FIG. 2, the vehicle subsystems 110 may also include anemergency stop functionality 127. The emergency stop 127 may be anysuitable switch configured to provide, for example, stop, pause, or runcommands to the vehicle control system 100 to either stop, temporarilyinterrupt, or initiate the operation of the vehicle 102. In oneembodiment, the emergency stop functionality 127 may cause a full brakecommand to be provided to the braking system 116. The full brake commandresults in the service brakes being applied in full to stop the vehicle102 as quickly as possible.

The vehicle subsystems 110 may also include an odometer 128. Theodometer 128 may be used to provide information regarding the movementof the vehicle 102 (e.g., distance traveled) to the vehicle controlsystem 100 in order to enhance the ability of the vehicle control system100 to determine the position or movement of the vehicle 102. Theodometer may also be used by the vehicle control system 100 to performdead reckoning navigation.

The path planning module 200 is configured to determine the desiredtrajectory of the vehicle 102 and provide that trajectory to the vehiclemanagement system 106. The trajectory includes a desired path along theground as well as the desired speeds and boundary area. The desiredtrajectory may be determined using path and speed constraints definedbefore the vehicle 102 begins operating autonomously (e.g., pre-missionplanning stage). As mentioned above in connection with the navigationmodule 204, the route that the vehicle 102 follows may be definedbeforehand and loaded into the vehicle control system 100. For example,the route may be defined in terms of a series of waypoints that define apath along the ground, a path boundary, and/or speed constraints foreach section of the path. The path planning module 200 provides reactivepath corrections to this nominal path to account for current conditions,such as vehicle dynamic limits, obstacles (positive obstacles such aslarge rocks, trees, etc. and negative obstacles such as road edges,drop-offs, and cliffs), terrain grade, and so forth.

In one embodiment, the path planning module 200 may be configured to usea tree algorithm that branches from the base at the current waypoint.The tree build function may be constrained by the pre-defined pathboundary and/or speed so that the resulting tree is not too large toprocess. Braches of the tree are computed using a model of the vehicle102 (e.g., steering system and vehicle dynamics) to ensure that thecandidate paths are drivable. One potentially suitable model isdescribed in U.S. Provisional Patent Application No. 60/723,363,entitled “Vehicle Control System and Method,” filed on Oct. 4, 2005,which is hereby incorporated herein by reference in its entirety. Thetree algorithm may be derived from the Rapidly-exploring Random Tree(RRT) path planner where the growth of the tree is limited to a fixednumber of branches (levels).

The tree represents a series of candidate paths for the vehicle 102 totravel along. The vehicle control system 100 selects a path from thevarious candidate paths based on a scoring algorithm that considersdistance from the route centerline, path curvature, obstacle avoidance,boundary area constraints, and so forth. The path planning module 200may generate at least 100 candidate paths, at least 1000 candidatepaths, or at least about 2000 candidate paths each planning cycle.Typically, the path planning module 200 performs a path analysis eachtime a waypoint is reached. The path planning module 200 may also beconfigured to adjust the maximum speed of the vehicle 102 to account forpath geometry and current conditions. The initial desired speed may beset to the maximum determined during the pre-mission planning stage. Thespeed management component of the path planning module 200 may beconfigured to adjust the initial set speed depending on conditions. Inone embodiment, the speed management component of the path planningmodule 200 may be configured to reduce the maximum speed of each sectionof the path depending on the current conditions.

In another embodiment, the path planning module 200 may be configured tocontinually calculate and adjust the path while the vehicle 102 istraveling (e.g., real-time path planning). In yet another embodiment,the path planning module 200 may be configured to reevaluate the path ifthe vehicle 102 encounters a situation that prevents the vehicle 102from continuing on the original path (e.g., a washed out road, fallentree, rock slide, etc.). In this situation, the path planning module 200may be configured to determine the best way for the vehicle 102 toproceed to the waypoint. The path planning module 200 may include orhave access to some of the same information that may be included in thenavigation module 204 such as topographical maps, road maps, aerial orsatellite images, and so forth, to allow the path planning module 200 todetermine the best path for the vehicle 102.

FIG. 13 shows a graphical representation of a path generated by the pathplanning module 200. In FIG. 13, the vehicle 102 is represented by thelong rectangular box. The sequence of boxes 208 represents the path thatis loaded into the vehicle management system 106 before the vehicle 102begins operating autonomously. The numbers identified by the referencenumeral 210 represent the real-time path generated by the path planningmodule 200. FIG. 13 also shows obstacles 212 detected by the terraindetection system 104. As shown in FIG. 13, the path 210 of the vehicle102 is adjusted to the right of the center of the pre-loaded path toavoid obstacles in the turn. The data boxes (e.g., control data, commandresponse, state data, path data) in FIG. 13 show data associated withthe path, vehicle state, and control state of the vehicle 102.

FIG. 14 is an illustration of the path 224 (the path 224 is the sequenceof numbers shown in FIG. 14) generated by the path planning module 200which shows obstacles 222 detected using the first LIDAR system 103.Similarly, FIG. 15 is an illustration of the path 226 (the path 226 isthe sequence of numbers shown in FIG. 15) generated by the path planningmodule 200 which shows obstacles 228 detected using the second LIDARsystem 105.

The vehicle management system 106 controls the movement of the vehicle102 along the path by providing wheel angle commands to the steeringsystem 112 the wheel angle commands move the vehicle 102 along the pathdefined by the path planning module 200. This may be accomplished bycomputing deviations from the desired path and converting the deviationsinto steer angle commands that are sent to the steering servo.

The vehicle management system 106 may include a capture steering modeand a track steering mode. The capture steering mode refers to thesteering mode that is used based on the pre-loaded path data. The tracksteering mode refers to the steering mode that is used during normaloperation. Capture and track steering modes may be automaticallyselected based on current conditions.

The capture steering mode uses course error as the control parameter.The vehicle management system 106 creates a steer angle command thataligns the ground track of the vehicle with the direct bearing to thenext waypoint. This type of control may be referred to as homingcontrol. Typically, capture steering mode is typically only used whenthe vehicle 102 first begins autonomous operation

The track steering mode uses linear cross track deviation and crosstrack deviation rate to align the vehicle's path along the ground withthe waypoint course. Track angle error and steer angle command limitersmay be used to limit the commanded steer angle to values that areachievable by the vehicle 102. The command limiters incorporate vehicledynamic limits with margins built in to ensure that the vehicle does notget into an unsafe condition. This may also mean that the vehicle 102operates at levels below its maximum dynamic capability when inautonomous mode. The vehicle management system 106 may also anticipateturns so that the transition between traveling between waypoints may beaccomplished without overshoots.

The vehicle management system 106 is configured to monitor anddynamically change to conditions using information from the pathplanning module 200, the navigation module 204, the vehicle controlmodule 202, and the information database 206. The vehicle managementsystem 106 may be configured to handle a number of situations that mayarise during autonomous operation. When the situation occurs, thevehicle management system 106 is configured to proceed through certainoperations to address the situation.

Examples of situations that may arise include:

(1) transition to and from e-stop state—when the e-stop is activated,the vehicle management system 106 is configured to stop the vehicle 102.When the e-stop is deactivated, the vehicle management system 106 isconfigured to initiate normal operation.

(2) no valid path ahead—the vehicle 102 is commanded to stop and waitfor the vehicle management system 106 to obtain a valid path. If novalid path is found the vehicle management system 106 will back thevehicle 102 up and try again.

(3) obstacle detected behind vehicle while backing up—the vehiclemanagement system 106 stops the vehicle 102 and initiates normaloperation of the vehicle 102 to find a valid path ahead.

(4) a large course change requiring a back up maneuver—the vehiclemanagement system 106 operates the vehicle 102 around a three pointturn.

(5) narrow tunnel—the vehicle management system 106 guides the vehicle102 through the tunnel primarily using the LIDAR systems 103, 105.

(6) stuck between obstacles—the vehicle management system 106 implementsthe stuck behavior when the vehicle 102 cannot make progress along theroute because it is continually going back and forth so that it is stuckbetween obstacles. The vehicle management system 106 positions thevehicle 102 at different angles to search for a valid path. If no validpath is found, then the vehicle management system 106 ignores lowconfidence obstacles in an attempt to eliminate low confidenceobstacles. The last resort is to go forward along the pre-loaded routeignoring all obstacles.

The vehicle control system 100 may also be configured to detect acollision involving the vehicle 102. Upon detection of a collision, thevehicle control system 100 may be configured to run a diagnostic checkon each input and output device that is part of the vehicle controlsystem 100 to determine if all of them are online and functional.

The functionality of the vehicle management system 106 may be similar tothe Distributed Architecture for Mobile Navigation (DAMN) where thevehicle ordinarily follows the path generated by the path planningmodule 200 but the path can be overwritten depending on the currentconditions. However, in some embodiments, the DAMN architecture may bemodified to use a rules-based decision logic (instead of a complexvoting scheme) to determine when the path should be overwritten. The useof rules-based decision logic may be more deterministic and robust thanother solutions, which may render itself more useful in fleetapplications.

The system manager 108 is the module of the vehicle control system 100that allows a user to interface with the vehicle control system 100 toexecute control commands and review the status of various systems anddevices. The system manager 108 is also configured to continuouslymonitor the status of the various applications included in the vehiclecontrol system 100. If the system manager 108 determines that anapplication is no longer functioning normally, the system manager 108 isconfigured to stop and restart the application to return normalfunctionality. The vehicle control system 100 may be configured so thatif the system manager 108 fails, the vehicle control system 100 cancontinue operating.

In the context of a convoy of vehicles 102, the first vehicle 102 in theconvoy may be configured to operate autonomously. The remainder of thevehicles may operate autonomously as well, but instead of activelysensing and avoiding obstacles, each of the remaining vehicles may beconfigured to follow the one in front of it. This way there are not alarge number of vehicles 102 in the convoy operating to independentlyfind the best path to a destination. The vehicles 102 may be configuredso that if the lead vehicle 102 is disabled, the vehicle 102 behind thelead vehicle 102 may take over leading the convoy.

FIGS. 10-12 show another vehicle 302 which includes the vehicle controlsystem 100. The vehicle 302 may be a heavy duty tactical militaryvehicle. The vehicle 302 may be configured to function as a cargo truck(e.g., multiple configurations of a cargo truck that can carry differenttypes and amounts of cargo), a fuel servicing truck, a load handlingsystem truck (e.g., includes a lift arm that loads pallets onto thevehicle), a bridge transport vehicle, and a recovery vehicle (e.g.,wrecker vehicle) with cranes and winches. The vehicle 302 may beconfigured so that it is capable of being transported by a C130airplane.

The terms recited in the claims should be given their ordinary andcustomary meaning as determined by reference to relevant entries (e.g.,definition of “plane” as a carpenter's tool would not be relevant to theuse of the term “plane” when used to refer to an airplane, etc.) indictionaries (e.g., consensus definitions from widely used generalreference dictionaries and/or relevant technical dictionaries), commonlyunderstood meanings by those in the art, etc., with the understandingthat the broadest meaning imparted by any one or combination of thesesources should be given to the claim terms (e.g., two or more relevantdictionary entries should be combined to provide the broadest meaning ofthe combination of entries, etc.) subject only to the followingexceptions: (a) if a term is used herein in a manner more expansive thanits ordinary and customary meaning, the term should be given itsordinary and customary meaning plus the additional expansive meaning, or(b) if a term has been explicitly defined to have a different meaning byreciting the term followed by the phrase “as used herein shall mean” orsimilar language (e.g., “herein this term means,” “as defined herein,”“for the purposes of this disclosure [the term] shall mean,” etc.).References to specific examples, use of “i.e.,” use of the word“invention,” etc., are not meant to invoke exception (b) or otherwiserestrict the scope of the recited claim terms. Accordingly, the subjectmatter recited in the claims is not coextensive with and should not beinterpreted to be coextensive with any particular embodiment, feature,or combination of features shown herein. This is true even if only asingle embodiment of the particular feature or combination of featuresis illustrated and described herein. Thus, the appended claims should beread to be given their broadest interpretation in view of the prior artand the ordinary meaning of the claim terms.

As used herein, spatial or directional terms, such as “left,” “right,”“front,” “back,” and the like, relate to the subject matter as it isshown in the drawing FIGS. However, it is to be understood that thesubject matter described herein may assume various alternativeorientations and, accordingly, such terms are not to be considered aslimiting. Furthermore, as used herein (i.e., in the claims and thespecification), articles such as “the,” “a,” and “an” can connote thesingular or plural. Also, as used herein, the word “or” when usedwithout a preceding “either” (or other similar language indicating that“or” is unequivocally meant to be exclusive—e.g., only one of x or y,etc.) shall be interpreted to be inclusive (e.g., “x or y” means one orboth x or y). Likewise, as used herein, the term “and/or” shall also beinterpreted to be inclusive (e.g., “x and/or y” means one or both x ory). In situations where “and/or” or “or” are used as a conjunction for agroup of three or more items, the group should be interpreted to includeone item alone, all of the items together, or any combination or numberof the items. Moreover, terms used in the specification and claims suchas have, having, include, and including should be construed to besynonymous with the terms comprise and comprising.

Unless otherwise indicated, all numbers or expressions, such as thoseexpressing dimensions, physical characteristics, etc. used in thespecification are understood as modified in all instances by the term“about.” At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the claims, each numericalparameter recited in the specification or claims which is modified bythe term “about” should at least be construed in light of the number ofrecited significant digits and by applying ordinary rounding techniques.Moreover, all ranges disclosed herein are to be understood to encompassany and all subranges subsumed therein. For example, a stated range of 1to 10 should be considered to include any and all subranges between andinclusive of the minimum value of 1 and the maximum value of 10; thatis, all subranges beginning with a minimum value of 1 or more and endingwith a maximum value of 10 or less (e.g., 5.5 to 10).

What is claimed is:
 1. A vision system comprising: a processor; and aplurality of cameras each of which is configured to be communicativelycoupled to the processor, the plurality of cameras including at leastthree cameras; wherein the processor receives input from differentcombinations of the plurality of cameras which are selected based on aparameter that is associated with the status of the vehicle and/or isassociated with the surrounding environment, and wherein the visionsystem is configured to be used with a vehicle, and wherein theplurality of cameras includes a first camera, a second camera, and athird camera, and wherein the processor receives input from: (a) thefirst camera and the second camera when the vehicle is in a first speedrange, (b) the first camera and the third camera when the vehicle is ina second speed range, and (c) the second camera and the third camerawhen the vehicle is in a third speed range.
 2. The vision system ofclaim 1 wherein the vision system is a stereo vision system which usesthe input from the different combinations of the plurality of cameras todetect obstacles.
 3. The vision system of claim 2 wherein the parameterincludes a rate the obstacles are detected by the stereo vision system.4. The vision system of claim 2 wherein the parameter includes a size ofthe obstacles detected by the stereo vision system.
 5. The vision systemof claim 1 wherein the vision system is configured to be used with avehicle, and wherein the parameter includes a speed of the vehicle. 6.The vision system of claim 1 wherein the vision system is configured tobe used with a vehicle, and wherein the parameter includes a steeringangle of the vehicle.
 7. The vision system of claim 1 wherein the atleast three cameras are each a different type of camera.
 8. The visionsystem of claim 1 wherein at least one of the pluralty cameras includesan infrared camera.
 9. The vision system of claim 1 wherein the visionsystem is configured for use with an autonomous vehicle.
 10. The visionsystem of claim 1 wherein at least one of the plurality of camerasincludes a video camera.
 11. A vision system comprising: a processor;and a plurality of cameras each of which is configured to becommunicatively coupled to the processor, the plurality of camerasincluding at least three cameras; wherein the processor receives inputfrom different combinations of the plurality of cameras which areselected based on a parameter that is associated with the status of thevehicle and/or is associated with the surrounding environment, andwherein the different combinations of the plurality of cameras includesa first combination of cameras which includes two cameras spaced apartby a first distance and a second combination of cameras which includestwo cameras spaced apart by a second distance, the first distance beinglarger than the second distance, wherein the vision system is used toidentify one or more objects at varying distances from the plurality ofcameras, and wherein the processor receives input from the firstcombination of cameras when the one or more objects are at a thirddistance and the processor receives input from the second combination ofcameras when the one or more objects are at a fourth distance, the thirddistance being larger than the fourth distance.
 12. An autonomousvehicle, comprising: a microprocessor-based vehicle control system; asteering system, a braking system, a throttle system, and a transmissionsystem each of which is in communication with the vehicle controlsystem; and a plurality of cameras which are in communication with thevehicle control system; wherein the vehicle control system is configuredto receive input from different combinations of the plurality of cameraswhich are selected based on a parameter that is associated with thevehicle and/or is associated with the surrounding environment, andwherein the plurality of cameras includes a first camera, a secondcamera, and a third camera, and wherein the vehicle control system isconfigured to receive input from: (a) the first camera and the secondcamera when the vehicle is in a first speed range, (b) the first cameraand the third camera when the vehicle is in a second speed range, and(c) the second camera and the third camera when the vehicle is in athird speed range.
 13. The vehicle of claim 12 wherein the plurality ofcameras includes a first camera, a second camera, and a third camera,and wherein the different combinations of the plurality of camerasincludes: (a) the first camera and the second camera, (b) the firstcamera and the third camera, and (c) the second camera and the thirdcamera.
 14. The vehicle of claim 13 wherein the first camera, the secondcamera, and the third camera are coupled to the vehicle andasymmetrically spaced apart from each other.
 15. The vehicle of claim 13wherein the parameter includes a speed of the vehicle.
 16. The vehicleof claim 12 wherein the parameter includes a steering angle of thevehicle.
 17. The vehicle of claim 12 wherein the vehicle control systemis configured to use the input from the plurality of cameras to detectobstacles, and wherein the parameter includes a rate of obstaclesdetected by the vision system.
 18. The vehicle of claim 12 wherein thevehicle control system is configured to use the input from the pluralityof cameras to detect obstacles, and wherein the parameter includes asize of at least one obstacle from the obstacles detected by the visionsystem.
 19. The vehicle of claim 12 wherein the plurality of camerasincludes an infrared camera.
 20. The vehicle of claim 12 wherein thevehicle control system includes a stereo vision system which receivesthe input from the different combinations of the plurality of cameras.21. The vehicle of claim 12 further comprising: a compressed air supplysupported by the vehicle platform; and a cleaning device coupled to thecompressed air supply and configured to direct compressed air towards alens of at least one of the plurality of cameras.
 22. The vehicle ofclaim 21 wherein the compressed air supply is a compressed air supplyfor the braking system.
 23. The vehicle of claim 21 wherein the cleaningdevice includes an air knife.
 24. A method comprising: detecting aparameter that is associated with a vehicle and/or is associated withthe surrounding environment; and selecting one of a plurality ofcombinations of cameras coupled to the vehicle based on the parameter,wherein selecting one of a plurality of combinations of camerascomprises selecting: (a) a first camera and a second camera when thevehicle is in a first speed range, (b) the first camera and a thirdcamera when the vehicle is in a second speed range, and (c) the secondcamera and the third camera when the vehicle is in a third speed range.25. The method of claim 24 wherein the cameras are asymmetrically spacedapart from each other.
 26. The method of claim 24 wherein the parameterincludes a speed of the vehicle.
 27. The method of claim 24 wherein theparameter includes a steering angle of the vehicle.
 28. A vision systemcomprising: a processor; and a plurality of cameras each of which isconfigured to be communicatively coupled to the processor, the pluralityof cameras including at least three cameras; wherein the processorreceives input from different combinations of the plurality of camerasbased on the status of the vehicle and/or the surrounding environment,and wherein the at least three cameras includes a first camera, a secondcamera, and a third camera, and wherein the vision system is configuredto obtain input from the first camera and the second camera when thevehicle is in a first speed range, obtain input from the first cameraand the third camera when the vehicle is in a second speed range, andobtain input from the second camera and the third camera when thevehicle is in a third speed range.
 29. A vision system for use with avehicle, the vision system being configured to obtain input from atleast three cameras coupled to the vehicle by switching betweendifferent combinations of the at least three cameras based on the statusof the vehicle and/or the surrounding environment, wherein the at leastthree cameras includes a first camera, a second camera, and a thirdcamera, and wherein the vision system is configured to obtain input fromthe first camera and the second camera when the vehicle is in a firstspeed range, obtain input from the first camera and the third camerawhen the vehicle is in a second speed range, and obtain input from thesecond camera and the third camera when the vehicle is in a third speedrange.
 30. The vision system of claim 29 comprising a processorconfigured to process the input from the at least three cameras.
 31. Thevision system of claim 29 wherein the at least three cameras areasymmetrically spaced apart from each other.
 32. The vision system ofclaim 29 wherein the vision system is configured to obtain the inputfrom the at least three cameras by switching between differentcombinations of the at least three cameras based on the speed of thevehicle.
 33. The vision system of claim 29 wherein each of the at leastthree cameras includes a video camera.